Sanitary centrifugal pump



July 2, 1963 H. ELENBAAS SANITARY CENTRIFUGAL PUMP Filed May 2, 1960 INVENTOR. f/FFMA/V Elf/Vfi/Mfi' A rrom/f/ United States Patent 3,095,821 SANITARY CENTRIFUGAL PUMP Herman Elenbaas, P.O. Box 273, Lyndon, Wash. Filed May 2, 1960, Ser. No. 26,038 1 Claim. (Cl. 103103) The pump of the present invention is of the centrifugal type and is constructed of material enabling it to be used for pumping liquid intended for food purposes, such as milk.

A principal object of the invention is to provide a pump of suflicient capacity for use with farm milk storage tanks, such as for cleaning them, and which will be constructed of material which is noncorrodible, which will not taint milk, and which can be cleaned and disinfected easily.

Specifically, it is an object to construct such a pump of molded plastic material of such construction that it will embody a minimum number of parts which can be molded easily, assembled and disassembled quickly, and which will have suflicient strength to withstand rotation at high speed.

In providing a pump having such characteristics, such pump includes only two principal parts contacted by the milk or other liquid being pumped one of which is the pump impeller and the other of which is the casing, both of which parts can be made of molded nylon as a suitable plastic material. In order to support the rotor adequately, the rotor is supported or guided at both sides of its central portion and the vanes have both edges supported, although the central portion of the impeller is hollow to enable a securing nut to be received in the central cavity.

FIGURE 1 is a top perspective view of the pump and a portion of the structure on which it is mounted, with parts broken away.

FIGURE 2 is an end elevation view of the pump, with parts broken away.

FIGURE 3 is a central sectional View through the pump taken on line 3-3 of FIGURE 2.

FIGURE 4 is an enlarged detail sectional view of mounting and rotating mechanism for the impeller.

FIGURE 5 is a top perspective View of the impeller, with parts broken away, viewing one side of the impeller, and FIGURE 6 is a top perspective view of the impeller viewing the opposite side of the impeller.

It is convenient for the pump of the present invention to be of the direct drive type and, since it is comparatively small and light, it can be mounted conveniently on an electric motor 1. On one end of this motor is mounted a ring 2 secured to the motor frame by bolts 3 and carrying a spider including legs 4 projecting convergently from the ring 2. These legs support the pump mounting plate 5 disposed parallel to and spaced from the ring 2. The power take-oflf shaft 6 extends from the motor 1 through a central aperture in the mounting plate 5 for the purpose of rotating the pump impeller.

The pump impeller, shown best in FIGURES 5 and 6, includes a mounting plate 7 having in its central portion the aperture 8 for receiving the end of the power take-off shaft 6. From one side of the plate 7 generally radial vanes 9 project which curve from their inner edges outwardly and rearwardly opposite to the direct-ion of rotation of the impeller. As seen best in FIGURE 6, the inner edges 10 of these vanes are spaced outward a considerable distance from the center of the circular plate 7 so as to leave a central cavity inwardly of the vanes. The generally radial edges of these vanes remote from the plate 7 are also connected by a centering ring 11 having a cylindrical outer surface which is disposed concentrically of the circular plate 7 and the end of such ring closer to the plate connects the radially inner portions of the edges of vanes 9 remote from plate 7. It is preferred that the 'ice 4x vanes 9 be integral with the plate 7 and with the cylindrical ring 11 so that such plate, vanes and ring are all formed integrally, such as by being molded in a single piece from plastic material such as nylon.

The central portion of the impeller plate 7 opposite the vanes 9 has in it a recess 12 encircling the aperture 8 in which is received a bushing ring 13 which is somewhat thicker axially than the axial depth of the recess 12 as is shown in FIGURE 4. The shaft 6 has a projection 14 at its outer end which is of smaller diameter than the main body of the shaft, is of approximately the same size as the central aperture 8 in the impeller plate 7, and is threaded. The shoulder formed at the base of the projection 14 is located on the shaft just beyond the outer face of the pump mounting plate 5. Preferably the aperture 8 of plate 7 is threaded complementally to the threads on the projection 14 so that the impeller plate can be screwed onto such projection. The impeller then may be secured in place by the locking cap nut 15, as shown in FIGURES 3 and 4. It will be seen in FIGURE 4 that this construction maintains the impeller plate 7 spaced slightly from the mounting plate 5 so as to minimize friction between the impeller and the mounting plate while the shaft 6 has a bearing fit in the aperture of the mounting plate and the engagement of the bushing 13 with the face of the mounting plate forms a thrust bearing.

The cap nut 15 should be of metal, as is the shaft 6, so that the threads of the projection 14 and the nut will not be stripped when the impeller is secured on the shaft even though the impeller is frequently removed and re placed. To prevent contamination of the liquid being pumped, the nut should be of stainless steel and it covers the shaft end against contact with the liquid being pumped. To insure against leakage along shaft 6, sealing mechanism for the shaft is provided at the side of mounting plate 5 opposite the impeller. Such sealing structure includes the annular flange 16 into which fits a metal collar 17. This collar has an inwardly projecting flange 18 at its end adjacent to the mounting plate 5 and an outwardly projecting flange 19 spaced somewhat from such end of the collar. Preferably the collar has an additional in wardly projecting flange 20 which is narrower than the flange 18 both axially and radially.

A ring 21 of rubber or other suitable gasket or sealing material is received between the outer flange 19 of collar 17 and the mounting plate 5 and an inner ring of rubber or other suitable gasket material 22 is received within the collar between the flange 18 and the flange 23 at the end of the collar opposite the flange 18, and fits around internal flange 20. The collar is then urged to the right, as seen in FIGURE 4, by spring 24 engaging the outwardly projecting flange 19, which presses the collar toward the backing plate 5 to squeeze the ring 21 between the collar flange 19 and such backing plate. The wiping contact of the sealing ring 22 with the periphery of shaft 6 will prevent escape of liquid which may pass through the aperture of backing plate 5 along the shaft 6 to the left beyond the flange 18. The ring 21 confined between the mounting plate 5, the collar 17 and the flanges 16 and 19 will prevent escape of such liquid outward between the flange 16 and the collar flange 19.

In mounting the impeller on shaft 6, the sealing structure described will first be applied to such shaft and then the mounting plate structure is put in place by sliding its central aperture over the end of the shaft. The mounting ring 2 can then be secured to the motor housing by bolts 3 which will draw the pump mounting structure to the left, as seen in FIGURE 3, to compress the spring 24 which urges the sealing structure firmly against the mounting plate 5. Next the bushing ring 13 is placed in the recess in the impeller plate 7 and such impeller plate is screwed onto the tip 14 of shaft 6 and secured in place by the nut 15. The internal diameter of the impeller ring 11 is large enough to enable the nut 15 to be passed through it into the central cavity of the impeller inwardly ot the vanes 9 and the inner edges 10 of such vanes'are spaced sufliciently from the nut, as shown in FIGURES 3 and 4, to enable a wrench to be inserted between the vanes into the central cavity of the impeller and placed on the nut so that it can be tightened on the shaft.

The impeller thus mounted on the power shaft 6 is covered and guided by the unitary casing including the end plate portion 25 and the deep axial flange 26 project ing from the outer edge of such end plate portion a dis tance at least as great as the width of the vanes 9. The central area of the end plate portion 25 has in it an aperture of a size to receive closely the ring 11 of the impeller and a tubular portion of the casing 27 having a cylindrical inner surface projects from such aperture in the direction opposite the flange 26. This tubular projection also fits closely about the ring 11 over the axial length of the ring and, as shown best in FIGURE 3, is then reduced in size to a cross section approximately equal to the internal cross section of the ring 11'. Such tubularextension serves as a central inlet for the pump.

The unitary pump casing is held in position enclosing the impeller by bolts 28 extending axially of the casing through bosses 2.9 which project outwardly from the flange 26 at locations spaced circumferentially of such flange. Four of such bosses are shown in FIGURE 2, but a smaller number or alarger number of such bosses could be provided, if desired. The bolts also extend through the mounting plate to hold the casing in place. The inner periphery of the flange 26, when the casing is thus installed, is disposed close to the outer ends of the impeller vanes 9. An outlet tube 30 is provided on the flange 26 extending general'ly circumferentially of the casing and opening at the inside of the flange 26 to provide an outlet for the liquid discharged by the pump.

To complete the installation, a hose 31, which preferably is of plastic material, is secured by a hose clamp 32 to the inlet tube 27, as shown in FIGURE 3, and a discharge hose 33 is secured by the hose clamp 34 to a nipple 35 screwed into the internally threaded end of the outlet tube 30.

It will be evident that, as the impeller is rotated by the shaft 6 turned by the electric motor in the direction indicated by the arrow in FIGURE 2, the outer periphery of the ring 11 will be guided by the aperture in the casing end plate portion 25 and by the tube 27 so as to prevent tilting or wobbling of the impeller and maintain the ring in a central position thus relieving or preventing stress on the impeller plate 7 at the location of its connection to shaft 6. Such ring also interconnects the edges of the vanes 9 opposite plate 7 so that they are adequately supported against strain resulting from stress tending to bend them about their edges integral with plate 7. At the same time, adequate space is provided in the central cavity of the impeller inwardly of the inner edges 10 of the vanes not only to enable a wrench to be applied to the nut 15 but to afford an ample opening for passage of liquid from the inlet tube 27 to the spaces between the vanes 9.

I claim as my invention:

A sanitary pump comprising an impeller of molded plastic material including a circular plate, vanes projecting edgewise axially from said plate, having their radially inner ends spaced outward from the center of said plate to provide an unobstructed central cavity in the impeller and each having one edge integral with said plate, the edges of said vanes remote from said plate being free from their outer ends inward over most of their radial extent and a ring interconnecting the radially inner cortiers of said vanes remote from said plate, having a cylindrical outer surface and an unobstructed interior and pro jecting axially from the radially inner ends of said vanes away from said plate, and a casing of molded plastic material having a portion encircling said impeller, a portion having a cylindrical inner surface cilosely encircling and guiding the cylindrical outer surface of said ring for rotation thereof and an inlet tube communicating with the unobstructed interior of said ring and said impeller cavity.

References Cited in the tile of this patent UNITED STATES PATENTS 1,809,526 Namur June 9, 1931 2,271,961 Wakernan Feb. 3, 1942 2,297,283 Berg Sept. 29, 1942 2,641,191 Buchi June 9, 1953 2,668,006 Larrecq Feb. 2, 1954 2,672,821 Montgomery Mar. 23, 1954 2,764,099 Wernert Sept. 25, 1956 2,791,182 Scheidl May 7, 1957 2,898,861 Wakeman Aug. 11, 1959 2,941,477 Dalton June 21, 1960 2,954,739 Lung Oct. 4, 1960 2,967,486 Spence Ian. 10, 1961 FOREIGN PATENTS 204,622 Germany Nov. 27, 1908 215,961 Great Britain May 22, 1924 

